1/*
  2 * linux/ipc/namespace.c
  3 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
  4 */
  5
  6#include <linux/ipc.h>
  7#include <linux/msg.h>
  8#include <linux/ipc_namespace.h>
  9#include <linux/rcupdate.h>
 10#include <linux/nsproxy.h>
 11#include <linux/slab.h>
 
 12#include <linux/fs.h>
 13#include <linux/mount.h>
 14#include <linux/user_namespace.h>
 15#include <linux/proc_ns.h>
 
 16
 17#include "util.h"
 18
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 19static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
 20					   struct ipc_namespace *old_ns)
 21{
 22	struct ipc_namespace *ns;
 
 23	int err;
 24
 25	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 26	if (ns == NULL)
 27		return ERR_PTR(-ENOMEM);
 28
 29	err = ns_alloc_inum(&ns->ns);
 30	if (err) {
 31		kfree(ns);
 32		return ERR_PTR(err);
 33	}
 34	ns->ns.ops = &ipcns_operations;
 35
 36	atomic_set(&ns->count, 1);
 
 
 
 37	err = mq_init_ns(ns);
 38	if (err) {
 39		ns_free_inum(&ns->ns);
 40		kfree(ns);
 41		return ERR_PTR(err);
 42	}
 43	atomic_inc(&nr_ipc_ns);
 
 
 
 
 
 
 
 44
 45	sem_init_ns(ns);
 46	msg_init_ns(ns);
 47	shm_init_ns(ns);
 48
 49	ns->user_ns = get_user_ns(user_ns);
 50
 51	return ns;
 
 
 
 
 
 
 
 
 
 
 
 
 
 52}
 53
 54struct ipc_namespace *copy_ipcs(unsigned long flags,
 55	struct user_namespace *user_ns, struct ipc_namespace *ns)
 56{
 57	if (!(flags & CLONE_NEWIPC))
 58		return get_ipc_ns(ns);
 59	return create_ipc_ns(user_ns, ns);
 60}
 61
 62/*
 63 * free_ipcs - free all ipcs of one type
 64 * @ns:   the namespace to remove the ipcs from
 65 * @ids:  the table of ipcs to free
 66 * @free: the function called to free each individual ipc
 67 *
 68 * Called for each kind of ipc when an ipc_namespace exits.
 69 */
 70void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 71	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
 72{
 73	struct kern_ipc_perm *perm;
 74	int next_id;
 75	int total, in_use;
 76
 77	down_write(&ids->rwsem);
 78
 79	in_use = ids->in_use;
 80
 81	for (total = 0, next_id = 0; total < in_use; next_id++) {
 82		perm = idr_find(&ids->ipcs_idr, next_id);
 83		if (perm == NULL)
 84			continue;
 85		rcu_read_lock();
 86		ipc_lock_object(perm);
 87		free(ns, perm);
 88		total++;
 89	}
 90	up_write(&ids->rwsem);
 91}
 92
 93static void free_ipc_ns(struct ipc_namespace *ns)
 94{
 
 
 
 
 
 95	sem_exit_ns(ns);
 96	msg_exit_ns(ns);
 97	shm_exit_ns(ns);
 98	atomic_dec(&nr_ipc_ns);
 99
 
 
 
 
100	put_user_ns(ns->user_ns);
101	ns_free_inum(&ns->ns);
102	kfree(ns);
103}
104
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
105/*
106 * put_ipc_ns - drop a reference to an ipc namespace.
107 * @ns: the namespace to put
108 *
109 * If this is the last task in the namespace exiting, and
110 * it is dropping the refcount to 0, then it can race with
111 * a task in another ipc namespace but in a mounts namespace
112 * which has this ipcns's mqueuefs mounted, doing some action
113 * with one of the mqueuefs files.  That can raise the refcount.
114 * So dropping the refcount, and raising the refcount when
115 * accessing it through the VFS, are protected with mq_lock.
116 *
117 * (Clearly, a task raising the refcount on its own ipc_ns
118 * needn't take mq_lock since it can't race with the last task
119 * in the ipcns exiting).
120 */
121void put_ipc_ns(struct ipc_namespace *ns)
122{
123	if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
124		mq_clear_sbinfo(ns);
125		spin_unlock(&mq_lock);
126		mq_put_mnt(ns);
127		free_ipc_ns(ns);
 
128	}
129}
130
131static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
132{
133	return container_of(ns, struct ipc_namespace, ns);
134}
135
136static struct ns_common *ipcns_get(struct task_struct *task)
137{
138	struct ipc_namespace *ns = NULL;
139	struct nsproxy *nsproxy;
140
141	task_lock(task);
142	nsproxy = task->nsproxy;
143	if (nsproxy)
144		ns = get_ipc_ns(nsproxy->ipc_ns);
145	task_unlock(task);
146
147	return ns ? &ns->ns : NULL;
148}
149
150static void ipcns_put(struct ns_common *ns)
151{
152	return put_ipc_ns(to_ipc_ns(ns));
153}
154
155static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
156{
 
157	struct ipc_namespace *ns = to_ipc_ns(new);
158	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
159	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
160		return -EPERM;
161
162	/* Ditch state from the old ipc namespace */
163	exit_sem(current);
164	put_ipc_ns(nsproxy->ipc_ns);
165	nsproxy->ipc_ns = get_ipc_ns(ns);
166	return 0;
167}
168
 
 
 
 
 
169const struct proc_ns_operations ipcns_operations = {
170	.name		= "ipc",
171	.type		= CLONE_NEWIPC,
172	.get		= ipcns_get,
173	.put		= ipcns_put,
174	.install	= ipcns_install,
 
175};

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * linux/ipc/namespace.c
  4 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
  5 */
  6
  7#include <linux/ipc.h>
  8#include <linux/msg.h>
  9#include <linux/ipc_namespace.h>
 10#include <linux/rcupdate.h>
 11#include <linux/nsproxy.h>
 12#include <linux/slab.h>
 13#include <linux/cred.h>
 14#include <linux/fs.h>
 15#include <linux/mount.h>
 16#include <linux/user_namespace.h>
 17#include <linux/proc_ns.h>
 18#include <linux/sched/task.h>
 19
 20#include "util.h"
 21
 22/*
 23 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
 24 */
 25static void free_ipc(struct work_struct *unused);
 26static DECLARE_WORK(free_ipc_work, free_ipc);
 27
 28static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
 29{
 30	return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
 31}
 32
 33static void dec_ipc_namespaces(struct ucounts *ucounts)
 34{
 35	dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
 36}
 37
 38static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
 39					   struct ipc_namespace *old_ns)
 40{
 41	struct ipc_namespace *ns;
 42	struct ucounts *ucounts;
 43	int err;
 44
 45	err = -ENOSPC;
 46 again:
 47	ucounts = inc_ipc_namespaces(user_ns);
 48	if (!ucounts) {
 49		/*
 50		 * IPC namespaces are freed asynchronously, by free_ipc_work.
 51		 * If frees were pending, flush_work will wait, and
 52		 * return true. Fail the allocation if no frees are pending.
 53		 */
 54		if (flush_work(&free_ipc_work))
 55			goto again;
 56		goto fail;
 57	}
 58
 59	err = -ENOMEM;
 60	ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL_ACCOUNT);
 61	if (ns == NULL)
 62		goto fail_dec;
 63
 64	err = ns_alloc_inum(&ns->ns);
 65	if (err)
 66		goto fail_free;
 
 
 67	ns->ns.ops = &ipcns_operations;
 68
 69	refcount_set(&ns->ns.count, 1);
 70	ns->user_ns = get_user_ns(user_ns);
 71	ns->ucounts = ucounts;
 72
 73	err = mq_init_ns(ns);
 74	if (err)
 75		goto fail_put;
 76
 77	err = -ENOMEM;
 78	if (!setup_mq_sysctls(ns))
 79		goto fail_put;
 80
 81	if (!setup_ipc_sysctls(ns))
 82		goto fail_mq;
 83
 84	err = msg_init_ns(ns);
 85	if (err)
 86		goto fail_put;
 87
 88	sem_init_ns(ns);
 
 89	shm_init_ns(ns);
 90
 
 
 91	return ns;
 92
 93fail_mq:
 94	retire_mq_sysctls(ns);
 95
 96fail_put:
 97	put_user_ns(ns->user_ns);
 98	ns_free_inum(&ns->ns);
 99fail_free:
100	kfree(ns);
101fail_dec:
102	dec_ipc_namespaces(ucounts);
103fail:
104	return ERR_PTR(err);
105}
106
107struct ipc_namespace *copy_ipcs(unsigned long flags,
108	struct user_namespace *user_ns, struct ipc_namespace *ns)
109{
110	if (!(flags & CLONE_NEWIPC))
111		return get_ipc_ns(ns);
112	return create_ipc_ns(user_ns, ns);
113}
114
115/*
116 * free_ipcs - free all ipcs of one type
117 * @ns:   the namespace to remove the ipcs from
118 * @ids:  the table of ipcs to free
119 * @free: the function called to free each individual ipc
120 *
121 * Called for each kind of ipc when an ipc_namespace exits.
122 */
123void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
124	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
125{
126	struct kern_ipc_perm *perm;
127	int next_id;
128	int total, in_use;
129
130	down_write(&ids->rwsem);
131
132	in_use = ids->in_use;
133
134	for (total = 0, next_id = 0; total < in_use; next_id++) {
135		perm = idr_find(&ids->ipcs_idr, next_id);
136		if (perm == NULL)
137			continue;
138		rcu_read_lock();
139		ipc_lock_object(perm);
140		free(ns, perm);
141		total++;
142	}
143	up_write(&ids->rwsem);
144}
145
146static void free_ipc_ns(struct ipc_namespace *ns)
147{
148	/*
149	 * Caller needs to wait for an RCU grace period to have passed
150	 * after making the mount point inaccessible to new accesses.
151	 */
152	mntput(ns->mq_mnt);
153	sem_exit_ns(ns);
154	msg_exit_ns(ns);
155	shm_exit_ns(ns);
 
156
157	retire_mq_sysctls(ns);
158	retire_ipc_sysctls(ns);
159
160	dec_ipc_namespaces(ns->ucounts);
161	put_user_ns(ns->user_ns);
162	ns_free_inum(&ns->ns);
163	kfree(ns);
164}
165
166static LLIST_HEAD(free_ipc_list);
167static void free_ipc(struct work_struct *unused)
168{
169	struct llist_node *node = llist_del_all(&free_ipc_list);
170	struct ipc_namespace *n, *t;
171
172	llist_for_each_entry_safe(n, t, node, mnt_llist)
173		mnt_make_shortterm(n->mq_mnt);
174
175	/* Wait for any last users to have gone away. */
176	synchronize_rcu();
177
178	llist_for_each_entry_safe(n, t, node, mnt_llist)
179		free_ipc_ns(n);
180}
181
182/*
183 * put_ipc_ns - drop a reference to an ipc namespace.
184 * @ns: the namespace to put
185 *
186 * If this is the last task in the namespace exiting, and
187 * it is dropping the refcount to 0, then it can race with
188 * a task in another ipc namespace but in a mounts namespace
189 * which has this ipcns's mqueuefs mounted, doing some action
190 * with one of the mqueuefs files.  That can raise the refcount.
191 * So dropping the refcount, and raising the refcount when
192 * accessing it through the VFS, are protected with mq_lock.
193 *
194 * (Clearly, a task raising the refcount on its own ipc_ns
195 * needn't take mq_lock since it can't race with the last task
196 * in the ipcns exiting).
197 */
198void put_ipc_ns(struct ipc_namespace *ns)
199{
200	if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) {
201		mq_clear_sbinfo(ns);
202		spin_unlock(&mq_lock);
203
204		if (llist_add(&ns->mnt_llist, &free_ipc_list))
205			schedule_work(&free_ipc_work);
206	}
207}
208
209static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
210{
211	return container_of(ns, struct ipc_namespace, ns);
212}
213
214static struct ns_common *ipcns_get(struct task_struct *task)
215{
216	struct ipc_namespace *ns = NULL;
217	struct nsproxy *nsproxy;
218
219	task_lock(task);
220	nsproxy = task->nsproxy;
221	if (nsproxy)
222		ns = get_ipc_ns(nsproxy->ipc_ns);
223	task_unlock(task);
224
225	return ns ? &ns->ns : NULL;
226}
227
228static void ipcns_put(struct ns_common *ns)
229{
230	return put_ipc_ns(to_ipc_ns(ns));
231}
232
233static int ipcns_install(struct nsset *nsset, struct ns_common *new)
234{
235	struct nsproxy *nsproxy = nsset->nsproxy;
236	struct ipc_namespace *ns = to_ipc_ns(new);
237	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
238	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
239		return -EPERM;
240
 
 
241	put_ipc_ns(nsproxy->ipc_ns);
242	nsproxy->ipc_ns = get_ipc_ns(ns);
243	return 0;
244}
245
246static struct user_namespace *ipcns_owner(struct ns_common *ns)
247{
248	return to_ipc_ns(ns)->user_ns;
249}
250
251const struct proc_ns_operations ipcns_operations = {
252	.name		= "ipc",
253	.type		= CLONE_NEWIPC,
254	.get		= ipcns_get,
255	.put		= ipcns_put,
256	.install	= ipcns_install,
257	.owner		= ipcns_owner,
258};